This revised competing continuation, focused on a cohort of young Australian twin pairs born 1964-1971, surveyed initially by mailed questionnaire in 1990-1992, seeks a further four years support for a study of the role of genetic and social factors, and their covariation and interaction, in the development and natural history of patterns of alcohol use, and of alcohol abuse and dependence, with a particular focus on alcohol problems and alcohol use in women. Telephone interviews will be conducted with some 4500 twins, to assess lifetime history of alcohol dependence and abuse (DSM-IIIR & IV), major depression and anxiety disorders, history of adolescent conduct problems smoking and illicit substance use, traumatic events and other early environmental experiences. Male like-ex and unlike-sex pairs, as well as female like-sex pairs, will be studied, in order to estimate the effects of genotype x gender interaction, and to maximize the precision of estimates of genetic contributions to alcoholism risk in women. Twelve month follow-up interviews will be conducted with pairs where at least one twin screened positive for alcohol dependence (either DSM-IIIR or IV) at stage 1, as well as with a small random sample of 100 male and 100 female unaffected twins. Additional assessments to be obtained at follow-up will include more detailed information about the time course and co-occurrence of problems with alcohol and other comorbid disorders; other substance dependence or abuse, anti-social personality disorder, somatization disorder, and history of oppositional-defiant problems; more detailed assessments of early environment; and measures of health-services utilization, economic and occupational status, and other variables that may be influenced by untreated alcohol problems. These data, together with interview data from an older cohort of twins surveyed by telephone during the current grant cycle (the 1981 cohort: N=6000 twins), and questionnaire data from both cohorts, will be used to test hypotheses about the pathways by which genetic and environmental influences on alcoholism risk arise, and the extent to which such influences vary as a function of gender and birth cohort.